in fact i know this solution but i have my security departement who doesn't want this : we need to have one database for intranet and one for internet.
to what extend do you want to share content? Do you want to move content objects between the two sites? Or perhaps merly show content from one site in the other?
In the former case I would recomend a webservice based on SOAP. It gives you the controll you need. In the latter, I would simply use RSS-export/import.
But I'm sure there are many other ways to achieve what you want as well :-)
